THIS invention relates to a process for producing (−)-menthol and similar compounds.
(−)-Menthol is one of the world's largest selling flavour compounds, with a production of about 11800 tons per annum. Its peppermint flavour and cooling sensation are used in many products, primarily in mentholated cigarettes and oral hygiene products, such as toothpaste, mouthwash and chewing gum. Pharmaceutical and healthcare products use menthol in a variety of product types, such as cough lozenges, shaving cream and topical analgesics.
Owing to seasonal variations and poor farming practices, the availability of natural menthol from the largest supplying countries, India and China, is sometimes erratic. In addition to this, only a limited amount of peppermint can be planted, thus limiting the supply of natural menthol. The remainder of the demand for menthol is met by synthetic menthol.
Organoleptically, natural and synthetic menthol are completely interchangeable; any slight differences have been largely eliminated through product development. Moreover, synthetic menthol has a purer and more consistent taste and odour profile since it does not contain the impurities present in natural menthol.
There is always a need for new processes for the production of (−)-menthol and similar compounds.